\begin{tikzpicture}[>=Stealth, scale=0.6]
    \draw [->] (-3.5, 0) -- (3.5, 0) node[anchor=north] {$x$};
    \draw [->] (0, -5.0) -- (0, 5) node[anchor=west] {$y$};
    \draw (0, 0) node [below left] {\small $O$};
    \foreach \x in {-2, -1, 1, 2} {
        \draw (\x, 0) -- (\x, 0.2) node [above]{\small $\x$};
    }
    \foreach \y in {1, ..., 3} {
        \draw (0, \y) -- (0.2, \y) node [right] {\small $\y$};
    }
    \foreach \y in {-3, ..., -1} {
        \draw (0, \y) -- (-0.2, \y) node [left] {\small $\y$};
    }

    \draw[domain=1.3:-1.3,samples=50] plot (\x, {-3*\x}) node [above] {$y = -3x$};
    \foreach \x in {-1, ..., 1} {
        \draw [fill=black] (\x, -3*\x) circle(0.1);
    }
    \draw [dashed] (0, -3) -- (1, -3) -- (1, 0);
\end{tikzpicture}

